112926-00-8Relevant articles and documents
The hydration behavior of Ca-P-Si system via mechanochemical treatment
Yu, Tao,Ye, Jiandong,Zhang, Shujiang
, p. 2990 - 2993 (2010)
In the present study, the Si-substituted amorphous calcium phosphate (Si-ACP) was prepared via a dry-mechanochemical method, and the hydration behavior of Si-ACP was investigated by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electronic microscopy, and the determination of the setting time and compressive strength. The results showed that the mechanochemical treatment had a great effect on the resolution property of Si-ACP, which induced the different hydration behavior. With the presence of Si, the hydration product of Si-ACP showed better results of cell proliferation and metabolic activity, which were characterized by the methyl thiazolyl tetrazolium assay (MTT) with mesenchymal stem cells. This work was expected to have a guiding effect on the study of calcium phosphate cement.
AFM studies on the difference in wear behavior between Si and SiO2 in KOH solution
Katsuki, Futoshi,Kamei, Kazuhito,Saguchi, Akihiko,Takahashi, Wataru,Watanabe, Junji
, p. 2328 - 2331 (2000)
Wear behavior between a Si tip and a SiO2 film in KOH solution at various pH values has been examined by using an atomic force microscope. We found that the Si tip removal amount strongly depended on the solution pH value and was at a maximum at pH 10.2-12.5. This result indicates that wear behavior of the Si tip is similar to that of actual chemical mechanical polishing of a Si wafer. It was also found that the Si removal volume in moles was approximately equal to that of SiO2 irrespective of the solution pH value. This equality implies that a Si-O-Si bridge is formed between one Si atom and one SiO2 molecule at the wear interface, followed by the oxidation of the Si tip, and finally the bond rupture by the tip movement and the silica species including the Si-O-Si bridge is dissolved in the KOH solution.
Study of Ge bonding and distribution in plasma oxides of Si1-xGex alloys
Seck,Devine,Hernandez,Campidelli,Dupuy
, p. 2748 - 2750 (1998)
Secondary ion mass spectroscopy (SIMS) and Fourier transform infrared (FTIR) absorption have been studied in thin oxides of Si1-xGex grown by plasma oxidation. SIMS analysis reveals that Ge can migrate to the oxide film surface leavi
Effect of Mie resonance on photocatalytic hydrogen evolution over dye-sensitized hollow C-TiO2 nanoshells under visible light irradiation
Yao, Xiaxi,Hu, Xiuli,Cui, Yingying,Huang, Jialei,Zhang, Wenjun,Wang, Xuhong,Wang, Dawei
, p. 750 - 754 (2021)
Light utilization is one of the key factors for the improvement of photocatalytic performance. Herein, we design C-TiO2 hollow nanoshells with strong Mie resonance for enhanced photocatalytic hydrogen evolution in a dye-sensitized system under visible light irradiation (λ ≥ 420 nm). By tuning the inner diameters of hollow nanoshells, the Mie resonance in hollow nanoshells is adjusted for better excitation of dye molecules, which thus greatly enhances the light utilization in visible light region. This work shows the potential of Mie resonance in nanoshells can be an alternative strategy to increase the light utilization for photocatalysis.
Synthesis of magnesium silicate by heat treatment of sols and mechanical activation of solid components
Dudkin,Vasyutin
, p. 751 - 755 (2011)
A layered magnesium silicate, an analog to natural talc, was synthesized by mechanical treatment of a mixture of magnesium hydroxide and hydrated silicic acid powders, as well as by heat treatment of aqueous dispersions containing magnesium hydroxide particles and silica sols prepared from different precursors.
Self-assembled-monolayer film islands as a self-patterned-mask for SiO2 thickness measurement with atomic force microscopy
Komeda,Namba,Nishioka
, p. 3398 - 3400 (1997)
A novel method for measuring ultrathin (2-12 nm) SiO2 film thickness is discussed. The process consists of: (1) formation of octadecyltrichlorosilane (OTS) self-assembled-monolayer (SAM) islands on SiO2 of which thickness to be measured, (2) removal of the SiO2 layers not covered by the OTS-SAM islands, and (3) measurement of the height difference between the etched and nonetched areas by atomic-force-microscopy. The OTS film is good resist against HF and its islands can be regarded as self-patterned-mask. Practical usefulness is demonstrated not only by the compatibility of the measured values but also by the short measurement period resulting from the -~-directness of the method.
Development of Highly Active Silica-Supported Nickel Phosphide Catalysts for Direct Dehydrogenative Conversion of Methane to Higher Hydrocarbons
Dipu, Arnoldus Lambertus,Nishikawa, Yuta,Inami, Yuta,Iguchi, Shoji,Yamanaka, Ichiro
, p. 199 - 212 (2022)
The direct dehydrogenative conversion of methane (DCM) to higher hydrocarbons was investigated over silica-supported nickel phosphide catalysts (NixPy/SiO2) over 1023?K. NixPy/SiO2 catalysts were prepared by precipitation method to promote formation of nickel phosphide (Ni2P) as an active phase for the DCM reaction. Characterization studies of the NixPy/SiO2 catalysts with different P/Ni molar ratios were conducted by a X-ray diffraction analysis, a H2-temperature-programmed reduction spectrum, a scanning electron microscopy image, a X-ray absorption spectroscopy and a N2-adsorption measurement. Catalytic activity tests for the DCM reaction were conducted using a conventional fixed-bed reactor. Products of C2H4 (ethylene), C2H6 (ethane), C2H2 (acetylene), C3H6 (propylene), C6H6 (benzene), C7H8 (toluene), C10H8 (naphthalene) and H2 were analyzed by GC-TCD and GC-FID instruments. Different degrees of the Ni2P phase and character were observed for the NixPy/SiO2 catalysts from characterization studies. Data from characterization studies indicated that smaller and dispersed Ni2P particles were obtained by precipitation method as compared to that of impregnation method. NixPy/SiO2 with a molar ratio of P/Ni = 3.0 showed optimum catalytic performance with 3.28% of methane conversion, 1.93% of total product yield, and 60% of selectivity to hydrocarbons. The experimental results of the effects of reaction temperatures on the product distributions and activation energies indicated that the Ni2P phase successfully activated the C–H bond of methane and selectively converted to ethane. Ethane thermally converted to other higher hydrocarbons in the gas phase without the participation of the catalyst. Graphic Abstract: [Figure not available: see fulltext.].
Microporous SiO2 with huge electric-double-layer capacitance for low-voltage indium tin oxide thin-film transistors
Lu, Aixia,Sun, Jia,Jiang, Jie,Wan, Qing
, (2009)
Electric-double-layer (EDL) effect is observed in microporous SiO 2 dielectric films deposited at room temperature by plasma-enhanced chemical vapor deposition method. Indium tin oxide thin-film transistors gated by such microporous SiO2/
Preparation of titania/silica composite microspheres by sol-gel process in reverse suspension
Kimura, Isao,Kase, Takayuki,Taguchi, Yoshinari,Tanaka, Masato
, p. 585 - 597 (2003)
Silica gel microspheres were prepared by sol-gel process of silicon tetraethoxide in reverse suspension. Subsequently, titanium tetra-2-propoxide solution was added to the system for producing titania gel. The composite microspheres prepared were analyzed with optical microscopy, electron probe microanalysis, and X-ray diffraction. Lowering the titanium alkoxide concentration in the continuous phase was effective to depress the agglomeration of fine titania particles. When the titanium alkoxide solution was divided into four parts and each aliquot was added separately, the covering state with titania became more uniform. The composite microspheres prepared were suspended in dye solution under ultraviolet irradiation and examined for the possibility of treating wastewater. The dye concentration rapidly decreased more than with a commercial titania powder, due to the effects of both photodegradation and adsorption.
Sol-gel preparation and characterization of uniform core-shell structured LaInO3:Sm3+/Tb3+@SiO2 phosphors
Shang, Yongchen,Yang, Piaoping,Wang, Wenxin,Wang, Yanli,Niu, Na,Gai, Shili,Lin, Jun
, p. 837 - 844 (2011)
The core-shell structured LaInO3:Ln3+@SiO2 (Ln3+ = Sm3+, Tb3+) phosphors were realized by coating LaInO3:Ln3+ phosphors on the surface of silica microspheres via a modified Pechini sol-gel process. The phase, structure, morphology, and fluorescent properties of the materials were well characterized by means of X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform IR spectroscopy (FT-IR), photoluminescence (PL) spectra, cathodoluminescence (CL) spectra, and the kinetic decays, respectively. The results reveal that the obtained core-shell structured phosphors consist of amorphous silica core and crystalline LaInO3:Ln3+ shell, which keep the uniform spherical morphology of pure silica spheres with narrow size distribution. Upon excitation by ultraviolet (UV) irradiation or electron beam, the phosphors show the characteristic emission lines of Sm3+ (4G 5/2-6H5/2,7/2,9/2, orange) in LaInO 3:Sm3+@SiO2 and characteristic emissions of Tb3+ (5D4-7F6,5,4,3, green) in LaInO3:Tb3+@SiO2, respectively. This kind of phosphors may have potential applications in field emission displays (FEDs) based on their uniform shape, low-cost synthetic route, and diverse luminescent properties.
Radiation-induced luminescence and photoluminescence from sol-gel silica glasses and phosphosilicate glasses by 1 MeV H+ irradiations
Kitazawa, Sin-Iti,Yamamoto, Shunya,Asano, Masaharu,Ishiyama, Shintaro
, p. 159 - 165 (2004)
Radiation-induced luminescence (RIL), photoluminescence (PL) and PL excitation (PLE) spectra have been applied to the study of photon emission from sol-gel silica glasses and phosphosilicate glasses. The photoemissions from oxygen excess-related defects a
Inomata, Kiyoto,Ha, Hyunkwon,Chaudhary, Khaliq A.,Koinuma, Hideomi
, p. 46 - 48 (1994)
Thompson, L. R.,Rocca, J. J.,Emery, K.,Boyer, P. K.,Collins, G. J.
, p. 777 - 779 (1983)
Silica-supported chlorometallate(iii) ionic liquids as recyclable catalysts for Diels-Alder reaction under solventless conditions
Chrobok, Anna,Jarz?bski, Andrzej,Latos, Piotr,Markiton, Magdalena,Matuszek, Karolina,Swad?ba-Kwa?ny, Ma?gorzata,Szymańska, Katarzyna
, p. 8129 - 8137 (2016)
A range of Lewis acidic metal chlorides were tested as homogeneous catalysts in a model Diels-Alder reaction; AlCl3and GaCl3performed best in terms of conversion andendo : exoselectivity. Based on this outcome, the corresponding chlorometallate(iii) ionic liquids were tested as homogeneous catalysts, without a decrease in performance compared to the chlorides. Finally, these ionic liquids were heterogenised by covalent tethering of the cation onto a multimodal porous silica support; such supported chlorogallate(iii) ionic liquids are reported for the first time. Supported chlorometallate(iii) ionic liquids were used as recyclable heterogeneous catalysts for the Diels-Alder reaction under solventless conditions. High yields (99%) and highendo-selectivities (95%) were obtained after very short reaction times (5 min) at near-ambient temperature (25 °C).
Depth-resolved micro-Raman study of porous silicon at different oxidation states
Moreno,Agullo-Rueda,Montoya,Marcos,Gonzalez-Velasco,Guerrero-Lemus,Martinez-Duart
, p. 2166 - 2168 (1997)
Photoluminescence (PL) and Raman spectra were measured along a cross section of porous silicon films at different oxidation times after application of anodic current transients. The average crystallite size was determined from the Raman spectra with the standard phonon confinement model Before oxidation, the PL emission energy and crystallite size were found to be independent of the layer depth. Also, the integrated PL emission was larger for the middle layers. The effect of oxidation was a blueshift of the PL band and a decrease in the integrated emission for the outer layers. The crystallite size increases for all layers, particularly the outer ones.
Strong blue and violet photoluminescence and electroluminescence from germanium-implanted and silicon-implanted silicon-dioxide layers
Rebohle,Von Borany,Yankov,Skorupa,Tyschenko,Froeb,Leo
, p. 2809 - 2811 (1997)
The photoluminescence (PL) and electroluminescence (EL) properties of Ge-implanted SiO2 layers thermally grown on a Si substrate were investigated and compared to those of Si-implanted SiO2 films. The PL spectra from Ge-implanted SiO2 were recorded as a function of annealing temperature. It was found that the blue-violet PL from Ge-rich oxide layers reaches a maximum after annealing at 500°C for 30 min, and is substantially more intense than the PL emission from Si-implanted oxides. The neutral oxygen vacancy is believed to be responsible for the observed luminescence. The EL spectrum from the Ge-implanted oxide after annealing at 1000°C correlates very well with the PL one, and shows a linear dependence on the injected current. The EL emission was strong enough to be readily seen with the naked eye and the EL efficiency was assessed to be about 5×10-4.
Alkali metals extraction reactions with the silicides Li15Si4 and Li3NaSi6: Amorphous Si versus allo -Si
Zeilinger, Michael,Jantke, Laura-Alice,Scherf, Lavinia M.,Kiefer, Florian J.,Neubüser, Gero,Kienle, Lorenz,Karttunen, Antti J.,Konar, Sumit,H?ussermann, Ulrich,F?ssler, Thomas F.
, p. 6603 - 6612 (2014)
The silicides Li15Si4 and Li3NaSi6 were subjected to chemical extraction of the alkali metal component by liquid ammonia and ethanol, respectively, which after washing yielded black powders of amorphous silicon. The investigated reactions are interesting with respect to both the formation of novel Si modifications and the delithiation process in Si anode materials. The products termed a-Si (from Li15Si4) and a-allo-Si (from Li3NaSi6) were characterized by a combination of methodologies (X-ray diffraction, transmission electron microscopy, differential thermal analysis, Raman, atomic absorption, and energy-dispersive X-ray spectroscopy) which revealed (i) a porous microstructure for a-Si built from spherically shaped particles with sizes around 10 nm, (ii) partial surface oxidation of both materials and (iii) the presence of nanocrystalline Si in both materials. The result of the protic oxidation of Li3NaSi6 is at variance with earlier findings reporting the formation of a crystalline bulk allotrope of silicon (allo-Si) from the topotactic combination of silicon layers present as polyanions in Li3NaSi6. Additionally, quantum chemical calculations show that silicon layers in Li3NaSi6 cannot combine to energetically favorable allotropic forms of Si. This is different from Li7Ge12, where polyanionic germanium layers topotactically convert to the germanium allotrope m-allo-Ge upon oxidation.
Gold aggregates on silica templates and decorated silica arrays for SERS applications
Castillo,De La Rosa,Pérez
, p. 301 - 306 (2011)
In this work, we report the fabrication and characterization of size controllable gold nanoparticles (NPs) aggregates for their application in surface enhanced Raman scattering (SERS). Aggregates were prepared using two methodologies: (i) by using silica
Katz, A.,Feingold, A.,Chakrabarti, U. K.,Pearton, S. J.,Jones, K. S.
, p. 2552 - 2554 (1991)
Hosono, Hideo,Matsunami, Noriaki
, (1993)
THIN SILICON DIOXIDE USING THE RAPID THERMAL OXIDATION (RTO) PROCESS FOR TRENCH CAPACITORS.
Miyai,Yoneda,Oishi,Uchida,Uchida,Inoue
, p. 150 - 155 (1988)
Growth and electrical characteristics of thin silicon dioxide using the rapid thermal oxidation (RTO) process have been studied for planar and trench capacitors. Growth of silicon dioxide follows the linear-parabolic model. The activation energies of the linear rate constant B/A and the parabolic rate constant B are found to be 1. 98 and 1. 42 ev, respectively. Good electrical characteristics can be achieved by increasing the oxidation temperature from 1000 degree to 1150 degree C. For the trench capacitors oxidized at 1150 degree C, it is found that oxide breakdown occurs dominantly at the fields 10 to approximately 12 mv/cm, the leakage current density is 3 multiplied by 10** minus **1 A/cm**2 and the interface-state density is 3 multiplied by 10**1****1 A/cm**2 and the interface-state density is 3 multiplied by 10**1**0 cm** minus **2. The RTO process is proved to be a promising technique for the fabrication of trench capacitors.
Mantl, S.,Dolle, M.,Mesters, St.,Fichtner, P. F. P.,Bay, H. L.
, p. 3459 - 3461 (1995)
The influence of high-energy electron irradiation and boron implantation on the oxide thickness in the SiO2/Si system
Kurmaev,Shamin,Galakhov,Makhnev,Kirillova,Kurennykh,Vykhodets,Kaschieva
, p. 6969 - 6978 (1997)
The SiO2/Si system exposed to irradiation with 11-12 MeV electrons was studied by soft-x-ray emission spectroscopy using the variable-exciting-electron-energy, optical ellipsometry, and nuclear reaction techniques. For the SiO2/Si system prepared on an n-substrate, oxidation of Si was observed, and the thickness of the SiO2 layer after electron irradiation was estimated. For the SiO2/Si system prepared on a p-Si substrate, irradiation-induced oxidation was not observed. It was found that preliminary boron implantation in the SiO2/n-Si system blocks oxidation of the n-Si substrate exposed to electron irradiation.
Observation and control of Si surface and interface processes for nanostructure formation by scanning reflection electron microscopy
Ichikawa, Masakazu
, p. 9861 - 9870 (1999)
We observe the oxidation process on clean Si surfaces using high-resolution scanning reflection electron microscopy and form nanostructures on them using focused electron-beam-(EB-) induced surface reactions. Si thermal oxidation occurs layer by layer, and the interface between the oxide film (2 film is selectively decomposed from the EB-irradiated area, resulting in the exposure of a clean Si substrate. The typical width of the clean Si 'open windows' is about 10 nm. Using selective reactions during heating after the deposition of Si and Ge films on the patterned samples, Si nanowires and Ge nanoislands with 10 nm size are formed on Si surfaces. Ga-adsorbed Si nanoareas and Ga nanodots are also formed by selective adsorption of Ga on the Si window areas.
NEW METHODS TO PREPARE HIGH-PURITY SILICA.
Aulich,Eisenrith,Urbach
, p. 1710 - 1717 (1984)
Two methods are described to prepare high-purity silica to be employed as a low-cost starting material for solar-grade silicon production. In the first process, abundantly available quartz sand is purified by fusing it with glass forming oxides to form a melt from which the glass fibers are drawn. Subsequent treatment of the fibers with hot HCl leads to an exchange whereby all non-siliceous oxides are removed from the glass network leaving an insoluble matrix of high-purity silica. The second method employs sodium hexafluosilicate (Na//2SiF//6 ), prepared from fluosilic acid, a by-product of the fertilizer industry. The Na//2SiF//6 is thermally decomposed to yield gaseous SiF//4 which is subsequently hydrolyzed in an ammonia solution. With both methods silica having a purity of greater than 99. 99% was obtained.
RhNPs supported onN-functionalized mesoporous silica: effect on catalyst stabilization and catalytic activity
Pulido-Díaz, Israel T.,Serrano-Maldonado, Alejandro,López-Suárez, Carlos César,Méndez-Ocampo, Pedro A.,Portales-Martínez, Benjamín,Gutiérrez-Alejandre, Aída,Salas-Martin, Karla P.,Guerrero-Ríos, Itzel
, p. 3289 - 3298 (2021/03/16)
Amine and nicotinamide groups grafted on ordered mesoporous silica (OMS) were investigated as stabilizers for RhNPs used as catalysts in the hydrogenation of several substrates, including carbonyl and aryl groups. Supported RhNPs on functionalized OMS were prepared by controlled decomposition of an organometallic precursor of rhodium under dihydrogen pressure. The resulting materials were characterized thoroughly by spectroscopic and physical techniques (FTIR, TGA, BET, SEM, TEM, EDX, XPS) to confirm the formation of spherical rhodium nanoparticles with a narrow size distribution supported on the silica surface. The use of nicotinamide functionalized OMS as a support afforded small RhNPs (2.3 ± 0.3 nm), and their size and shape were maintained after the catalyzed acetophenone hydrogenation. In contrast, amine-functionalized OMS formed RhNP aggregates after the catalytic reaction. The supported RhNPs could selectively reduce alkenyl, carbonyl, aryl and heteroaryl groups and were active in the reductive amination of phenol and morpholine, using a low concentration of the precious metal (0.07-0.18 mol%).
Effects of temperature on the structure of mesoporous silica materials templated with cationic surfactants in a nonhydrothermal short-term synthesis route
Borówka, Anna,Skrzypiec, Krzysztof
, (2021/05/03)
This paper reports the influence of synthesis temperature on the structure of mesoporous silica materials templated with ionic surfactant. The results obtained allow for the prediction of optimal temperature value to be used in nonhydrothermal short-term synthesis. The model materials were mesoporous silicates of MCM-41 type. The samples were prepared under alkaline conditions using tetraethyl orthosilicate as a silica source and cetyltrimethylammonium bromide or octadecyltrimethylammonium bromide as templates. An increase in synthesis temperature led to a rougher surface and decrease in the long-range ordering of the materials obtained, while a slight temperature decrease produced additional porosity. The reasons for these structural disturbances were briefly explained. The best material structure was obtained by synthesis at a temperature slightly higher than the Krafft temperature of surfactant of the porosity template.
